Zelkova Carpinifolia Reservoir from Hyrcanian Forests, Northern Iran, a New Sacrifice of Ophiostoma Novo-Ulmi

BIODIVERSITAS ISSN: 1412-033X Volume 15, Number 1, April 2014 E-ISSN: 2085-4722 Pages: 48-52 Zelkova carpinifolia reservoir from Hyrcanian Forests, Northern Iran, a new sacrifice of Ophiostoma novo-ulmi AKRAM AHMADI1,♥, MOHAMMAD REZA KAVOSI1, HASSAN SOLTANLOO2 1Department of Forest Ecology, Faculty of Forest Sciences, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Golestan, Iran. Tel. /Fax. +98 171 2227867, ♥email: [email protected] 2Department of Plant Breeding and Biotechnology, Gorgan University of Agricultural Sciences and Natural Resources, Gorgan, Golestan, Iran. Manuscript received: 30 September 2013. Revision accepted: 31 October 2013. ABSTRACT Ahmadi A, Kavosi MR, Soltanloo H. 2014. Zelkova carpinifolia reservoir from Hyrcanian Forests, Northern Iran, a new sacrifice of Ophiostoma novo-ulmi. Biodiversitas 15: 48-52. Zelkova carpinifolia belongs to the Ulmaceae. It is the only species from Zelkova genus that has been distributed and is native to Iranian forests. This tree species is one of the valuable species that is comprised of endangered plants. Nevertheless, the most of reservoirs of this species have been faced to problems that fungal disease is one of the important and lethal disturbance. This study was conducted to identify the main disturbance which has been resulted in Z. carpinifolia decadence in Daland forest reservoir, North of Iran. The study has ensured that O. novo-ulmi is the fungal pathogen in this forest reservoir. It can be reminded that this pathogen had been previously found in Ulmus genus which has been created devastating event in these noteworthy reservoirs. Some symptoms which were observed in field comprising flagging and wilting of leaves. Bark beetle galleries and occlusion of xylem vessels were the other evidence of fungal disease. In light of laboratory results, the fungi colony was fluffy, light-colored and fast-growing. The different shapes of fungi growth like white fibrous and flower shape or dark petaloid shape were observed. Mean colony diameters of O. novo-ulmi were 3.72 ±0.16 mm/day in the dark at 20 °C. Simultaneously, Microscopic analysis of sexual and asexual systems of O. novo-ulmi using a light microscope, a stereo microscope, and a scanning electron microscope revealed that it had morphological features of Sporothix, Pesotum, yeast-like and Perithecium synanon morphology. Key words: Hyrcanian forest, Ophiostoma novo-ulmi, pathogen, symptom, Zelkova carpinifolia INTRODUCTION pathogens are commonly spread from tree by root grafts and bark beetles (Parker et al. 1941; Stipes et al. 1981; Webber and Gibbs 1989; Jacobi et al. 2007). This fungus Zelkova carpinifolia (Pall.) K. Koch, 1849 species from belongs to Ophiostomace, Ophiostomatales, Ascomycota Elm family (Ulmaceae) has been dispersed in East (Cannon and Kirk 2007). It is necessary to cited, this Anatolia, Caucasus, North and West of Iran. Ten species of fungus is declining Zelkova reservoirs by O. novo-ulmi Zelkova exist worldwide (Chen and Huang, 1999; Jin et al. with tangible rate which has been already observed on elm 2009) but only one of them is native to Iranian forests. It trees but today it has infected Zelkova trees, another genus has distribution in Golestan, Guilan, Mazandaran, of Ulmaceae. Azerbaijan, Kurdistan, Khorasan and Tehran provinces of The first comprehensive study about disease on Zelkova Iran. Zelkova carpinifolia with high quality wood and a trees has been reported by Rahnama (2004) that was due to beautiful canopy in northern forests are valuable. There are invasive and new strain of O. novo-ulmi. This strain is few reservoirs of Z. carpinifolia. The destruction of derived from O. ulmi that is divided to two subspecies of lowland forests and overly harvesting of Zelkova trees, also O. novo-ulmi ssp. novo-ulmi and O. novo-ulmi ssp. new disease, Dutch elm disease has caused rapid extinction americana. Unfortunately, this aggressive fungus is of this endangered species in the Z. carpinifolia reservoir, infecting other trees. Solla et al. (2 005) reported this in Daland Park, Golestan province, North of Iran. virulent fungal pathogen caused leaf wilting and Ophiostoma novo-ulmi is subspecies of O. ulmi that subsequent mortality to all three elm species (Ulmus spp.) caused second pandemic of Dutch elm disease (DED) and native to Europe and they had the first report in Iberian was more aggressive (Brasier 1996; Brasier et al. 2000; Peninsula. Paoletti 2006). O. novo-ulmi is separated into two distinct The objectives of this study were isolation and subspecies, novo-ulmi and americana (Brasier and Kirk identification of pathogen which has infected Z. 2001; Solla et al. 2008). This fungus creates a vascular wilt carpinifolia trees in North of Iran, which faced these disease (Sinclair and Campana 1978; Stipes and Campana Zelkova trees to extinction event with high rate. 1981; Brasier 1991; Dunn 2000; Jacobi et al. 2007). The AHMADI et al. – Zelkova carpinifolia reservoir from Hyrcanian Forests 49 Islamic Republic of Iran Daland Park 0 50 100 kilometer Figure 1. Location of the study site inside Daland park, the part of Hyrcanian forests, Golestan, North of Iran. MATERIALS AND METHODS Several fungal isolates were obtained from the stem segments of Z. carpinifolia. They grew well in the PDA Daland forest reservoir is one of rare reservoir of media. They showed the same morphology and growth Zelkova carpinifolia which has been located in Golestan pattern. Mycological properties of the fungi including province, North of Iran (Figure 1). This reservoir has been colony shape and color growth were described. encountered with rapid extinction due to fungi infection. The colony color of isolations incubated at 20°C was Sampling was performed from trees that had symptoms of first white, gradually creamy to creamy grayish with flower disease. Disks from stem segments of Z. carpinifolia trees shape in the center of Petri-dish on PDA. 7th days old were removed which showing characteristic dark spots in culture on potato dextrose agar has been shown in figure 5. cross section. Each tree had symptoms of DED but had Colony color on MEA represented that these fungi had evidence of infestation by bark beetles. Stems with necrotic colonies with white mycelium when young, turning dark symptoms were transferred to laboratory. Stems were cut brown as they became older. Colony shape of O. novo-ulmi into 0.5 cm thickness and after surface sterilizing cultured on PDA was white fibrous and in some older colonies, dark on WA 2% and were incubated at 20°C for up to three petaloid shape were formed at the center of Petri dishes. weeks in an incubation chamber. Mean colony diameters (± standard deviation) for O. novo- After growth of fungi, it cultured on potato dextrose ulmi, were 3.72 (±0.16) mm/day in the dark at 20 °C. agar and malt extract agar media. The strains were isolated. These results implied that there were sexual and asexual Liquid medium of potato dextrose used for preparing reproduction systems of Sporothix, the phase of spore suspension of fungi spore. Some fungi characteristic such production, is shown in figure 6. The Conidia were small as the growth rate, appearance characteristic of fungi, and oval shape which formed in clusters on short mycelium colony and spore were studied and compared with branches and have size of 2-3×4-6 µm (Figure 7). The mycology resources (Hunt 1965; De Hoog 1974; Barnett conidia produce mycelium via budding and germinating to and Hunter 1998; Eriksson et al. 2003). produce mycelium. These conidia represented asexual reproduction system. The isolate formed synnemata and droplets of conidia at RESULTS AND DISCUSSION the apex of the synnemata which denoted in Pesotum phase. In this phase, conidia masses on synnemata were The preliminary results indicated that limbs, leaves and almost yellow and oval shape with size of 1-3×2-5 µm. The sometimes entire of Z. carpinifolia trees shown symptoms conidia were located on the apex of synnemata with 1-2 of dieback. This is one of important symptoms which mm height. The scanning electron micrograph (SEM) of called flagging. It was really sensible in most of trees. In Conidia, synnemata and mycelium are shown in figure 8. flagging a branch or branches of tree had clearly symptoms In PDA rotating liquid media appeared yeast-like phase of wilting or yellowing of leaves while other branches were which individual cells germinated and the spores had healthy (Figure 2). Removing a patch of bark was evident different size. Yeast-like phase can be seen in figure 8. that there was bark beetle which had been created galleries Perithecium represents sexual system of fungi. In this underneath (Figure 3). Bark beetle galleries is one of step, Ascosporic were produced in a black fruiting body important symptoms of Dutch elm disease. In cross section called Perithecium (Figure 9). Ascosporic were spherical of stems, circles of brown dots, browning and infected with long neck Perithecium. Ascosporous were produced in sapwood was obvious that occurred death of xylem cells asci which degenerate inside of black fruiting body because of disturbance in water conducting (Figure 4.A). In (Perithecium). The measurements revealed that the neck Figure (4.B), occlusion of xylem vessels is observable that length was 460 (±175) micrometers and width of basis was are due to tyloses. 100 (±35). 50 BIODIVERSITAS 15 (1): 48-52, April 2014 2 3 4.A 4.B 5.A 5.B AHMADI et al. – Zelkova carpinifolia reservoir from Hyrcanian Forests 51 6 7 8 9 Figure 2. Symptoms of dieback in Z. carpinifolia trees Figure 3. Bark beetle galleries underneath the bark of Z. carpinifolia Figure 4. A and B, Cross section of an O. novo-ulmi infected Z. carpinifolia branch, showing characteristic dark spots in the wood Figure 5. A and B, Colony morphology of O.

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